Automatic telephone system.



D. S. HULFISH.

AUTOMATIC TELEPHONE SYSTEM APPLICATION FILED MAR.28,1911. RENEWED APR. H, 1914. 1, 1 18,490 Patented Nov. 24, 1914.

2 SHEETS-SHEET I.

D. S. HULFISH.

AUHHWA'IIC TELEPHONE SYSTEM.

APPLICATION FILED mmzm 1911 ranmww APR. 2, 1914. 1,1 13,4L9Q,

Patented Nov. 24, 1914.

w. LIX...

curt 1 STATE PATENT FFHJE.

DAVID S. HULFISH, 0F TORONTO, ONTARIO, CANADA, .ASSIGNOR T0 CANADIAN INDE- IENDENT TELEPHONE COMPANY, LIMITED, 0F TORQNTO, CANADA. A CORPORATION OF CANADA.

AUTOMATIC TELEPHONE SYSTEM.

Lil. Tithe-hm}.

T all whomit may concern:

Be it known that 1, Dawn 3. HnLFisi-t, a citizen of the Unitet States of America, and a resident of Toronto, county of York, Province oi Ontario and Dominion of Canada, have invented a new and useful Improvement in Automatic Telephone Systems, of which the following is a specification.

hity invention relates to automatic tele phone systems and has as its principal objec to provide a simple and'eliicient means whereby any one of a plurality of subscribers sub-stations may be automatically connected to a trunk line, the station during its coni'iection being guarded from interference by any other sub-station attempting to obtain connection with the trunlt.

A further object of my invention consists in providing a busy tone in the receiver of a sub-station attempting to connect with the trunk while the latter is busy.

A further object oi my invention consists in. providing a system of interconnected relays of which but one may be operated at any one time.

I accomplish these and other desideratu hereinafter disclosed by a novel system of relays and circuits whereby the telephone lines are normally maintained in connection with a. busy tone circuit'and are automatically switched from such connection to the trunk circuit by the removal of the receiver from the hook at the subscribers station first calling, the remaining sub-stations being locked in connection with the busy tone circuit during conversation over the trunk line by any one of the sub-stations. y

In the figures which accom any and form a part of this specification out in which like numerals designate corresponding parts throughout: Figure 1 illustrates in diagram four subscribers sub-stations and, a trunk line showing apparatus and circuit arrangements embodying my invention. Fig. 2 illustrates the apparatus and circuit arrangemcntof Fig. 1 and shows a sub-station in talking connection 'With the trunk line.

Referring to the figures, any number of' subscribers sub-stations, four of which I have illustrated for convenience at 1, 2, 3 and 4, are connected through the usual terminal and protective apparatus, which as it is so well known in the art is omitted from the diagram to avpid unnecessary complication, to a strip or" acks 7, 27 forpurposes ozt Specification of Letters Patent.

Patented Nov. 24-, 1914.

Renewed April 8. 1914. Serial No.. 830,538.

manual switching. The ring or longspring, contacts of the jflCkS 7, 27 are connected to one of the outside terminals of the A sides battery 200 through the respective battery bus wires 18 and 19 The tip or short-spring contacts of the jacks 7, 27 are connected through the series relays S, 28 respectively to the remaining outside terminals of the A sides of repeating coils 21, 51. The B side of the repeating coils 21, 51 have their inner terminals connected together'and their outside terminals connected to the talking armatures of relays 10, 50 respectively. The back contacts 13, 16 and 53, 56 of relays 10, 50 are connected to a pair of normal conductors 76 and 77 respectively over which the busy tone is supplied, thus norn'mlly placing the busy tone on the B sides oi. repeating coils 21, The front contacts ll. 15 and 5t, of relays 10, :30 are connected to"trunk conductors and 74 respectively, therebv bridgin' the B sides of a repeating coil as 51, across is e trunk line when relay 50 is energized. The armatures of the series relays 8, 28 are connected through conductors 17,. 57

with terminals of both the windings of relays 10, 50 respectively, while the front contacts 9, 29 of relays 8, 28 respectively are grounded at 24, 43 respectively.

Relays 10, 50 are connected through one of their other terminals with conductor 22 while the remaining terminals of the relays are connected to contacts 11, (31 of their respective relays. 'The contact, as 11, is arranged to be made by the operation of the signaling armature of a relay as 10, before contact 12 is broken by the same operation of the signaling armature. The signaling armature of relay l0 is'connected to con- -ductor 22,.whilc the back contact of the same number of sub-stations may he provided with trunking apparatus and circuits similar to those shown for substations 2 and 3, w lie the dotted extension of conductors 18, 1'9, 22, 76, 77, 75 74: and the dotted conductor 422 indicate that the circuits at the central oliice for station at may be modified by the removal of conductor .23 and more o'f'a'ppeiatus added conductor 28 h0W- ever being; connected as shown in. the circuit o'l the last group of apparatus added.

Referring to Fig. 2 in which the circuits are shown in aii'operated condition to allow ta'tion l to gain talking connection with the trunk line, the removal of the receirer from the hook at substation t closes a air cuit through the sub-station line conductors, battery hus wires 18 and 1.9 with battery 200 which energizes relay 28 causing it to operate its armature to make contact through front contact 9.9 between ground 43 and con ductor 57, thus placing ground upon the windings of relay and. closing a circuit through left heliuoi' the Winding of relay 50, conductor 2:2, signaling armature of relay 10, back contact 12 of relay 10, conductor 45, sil ualing' armature and back contact 32 oi re ay 30, conductor 46, signaling armature and back contact 42 of relay 40, conductor ii, ignaling armature and back contact 52 (not yet operated, see Fig. 1) of relay 30 conductor battery ions 18 to grounded hatter-y 200, thus energizing relay 50 to break contact between its tall-tine; armatures and busy tone contacts 53 and 56, thus removing; the calling line from the busy tone circuit and making contact between its talking armatures and front contacts 54: and 55, thus placing the line in talking connection with the trunk line 74, 75. Simultaneously with the operation of the talking armatures, the signaling armature of relay 50 is operated to make contact with front contact 61 before hack contact 52 is broken, thus maintaiiiing the'euergizing circuit for relay, 50 through one helix of its Winding as hitherto noted until front contact 61 is closed and hook contact 59; is finally broken, thereby providing an alternative energizing path for relay 50 from ground 43, contact 29 of series relay 25%, conductor 57, right helii of relay 50, front contact "61 of the signaling armature ofrelay 536 contact 52 conductor 93, hattery bus 18 to grounded battery 200, thus holding relay 50 energized and maintaining the connection of su'hrstation t with the trunk line. Should asuhscriher at another sub-station as l, attempt to obtain connection with the trunk line heing held loy'asub-station as 4', and in initiating the connection remove the receiver at station 1 from the hook, current will tlow from hattery 200', through the closed bridge atlstatiou l. thus energizing series relay 8 to closeita trout contect'and place ground iZl through contact 9 of relay 111 the energizing circuit at E5 upon tau iuconipl Qonductor l'Z, loft helix of relay l through conductor hraucl co duct r signaling armature and has contact relay '10, conductor 4-5, si ling Lil and back contact 52 of'rei so, conductor 4&6, signaling armat re and back contact 4% of relay ll), conductor torf ing a; use ture oi relay iii) a 22h point the cirol is broken as 50 is energiuedand back contact 52 is therefore open tron; he armature and groued does not me t grounded battery 2% Thus relay it) is not energized and the subscriber at sub-station 1 attempting; to connect".' with the lousy trunk line receives through the hack contactsoi relay 10 the busy tone in his receiver indi 1-- ing' to that subscriber that the trunk line is busy. Similarly a suhscriber-at any suh-station will hear the busy tone in his, receiver when attempting to connect his i'ustruirioi with a busy trunk.

The taps 17,537 of the uiudin 's of d 10 and 50 to ground through series-re o contacts 9, 29 respectively suhstam tially zero resistance, for should a series relay as 8, he operated to close its contact as e, by the removal of the receiver at the sub-- scrihers substation as l, in an attemrt the part of the subscriber to connect his instrumcntu'ith a truulr line heiug acid another station as i, the tap 5? om t Winding oil relay 50 to ground 2 3, through contact 29 will he shunted by the circui left helix of relay 50, conductor left helix of relay 1%, conductor 1'7, contact 9 of series relay 8 to ground 2%. its this shunt contains two left helices of the windings of relays l0 and 50, it is of relatively high resistauce compared t the resistance to around from the right "Winding of relay 50 through conductor 57, and the tan '5? to ground 43 through contact 29 of series relay 18 is substantially zero in resistance, it rollows that substantially all the current from grounded battery 200 thr ugh battery lous l8, conductor 23 and riglt helix"; of relay 50 flows to ground thro n the ground t 57 and the right helix of relay 50 instead oi through the left helix oi relay" 5G conductor 22 to ground through conductor l7 and contact 9 of reluyfi.

it will he noted that should a. suhscriher reniofve his receiver from the hoot: is at tempting a connection with the trunk andv find the trunk busy he may hold his re ceiv removed from the "hook auto matically oiotuin connection With the trunk the mists t the'su'bsoriher holding the trunk l'lElGflBP' .a some by hai'igin up his re 1 the operation of replacing the upon the hook at ti; tern 'nation or". a conversation over t e leases the series relay allows its talking and signaling armatures to return tonormal, removing the substation as 4, from the trunk line and replacing it on the busy tone circuit and simultaneously allowing the energization of relay as 10, which removes the busy tone from the receiver of the subscriber attempting the call and places that subscriber in talking connection with the trunk as hitherto exlained.

It will be further noted that as both relays as 8 and 10 are quick acting, the busy tone will not be perccptibly manifest in the receiver of a sub-station making connection with a trunk as the, operation of the hook switch in bridging ithe, instrument to the line and the operatidn of relays as 8 and 10, are substantially simultaneous.

While I have disclosed but one embodiment of my devicc,'it is obvious that numerous changes may be' made in the apparatus and circuits thereof without departing from the spirit or narrowing the scope of my invention.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is as follows:-

1. In an automatic telephone system, a plurality of telephone lines; a tone circuit; said telephone lines being normally connected to said tone circuit; a trunk line; and means for disconnecting any one of said telephone lines from said tone circuit and for connecting said telephone line to the said trunk circuit.

2. In an automatic telephone system, a plurality of tele hone lines; a tone circuit; said telephone lines being normally inductively connected to said tone circuit; a trunk line; and means for automatically disconnecting any one of said telephone lines from said tone circuit and connecting said te1ephone line to said trunk circuit.

3. In an automatic telephone system, a plurality of telephone lines, a busy tone circuit, said telephone lines being normally connected to said busy tone circuit, a trunk line, means for disconnecting any one of said telephone lines from said busy tone circuit and connecting said telephone line to said trunk line, means cooperative with said previously mentioned means for guarding said telephone line during connection with said trunk line from interference by any other telephone line atten'ipting cornice tion with said trunk line.

In an automatic telephone system, a plurality of telephone lines, a lousy tone cir uit, said telephone lines being normally inductively connected to said busy tone circuit, a trunk line, means for automatically disconnecting any one of said telephone lines from said busy tone circuit and conmeeting said telephone line to said trunk circuit and means cooperative with said pre- 'viously mentioned means for guarding said telephone line during connection with said trunk line from interruption by any other telephone line attempting connection with said trunk line.

5. In an automatic telephone system, a plurality of telephone lines, a plurality of relays at the central ollice each associated with one of said telephone lines, a busy tone circuit, said telephone lines being each nor mally connected to said busy tone circuit through contacts of its said associated relay, means for automatically operating one of said relays to b 'Oalc contact between its associated telephone line and said busy tone circuit and through other contacts on said relays place said telephone line in connection with said trunk line.

(5. in an automatic telephone system, a plurality of telephone lines, a plurality of relays at the central oiIice each associated with one of said telephone lines, a tone circuit, said telephone lines being each normally connected to said tone circuit through contacts of its said associated relay, means for automatically operating said relays to break contact between said telephone lines and the tone circuit and through other contacts on said relays place said telephone line in connection with said trunk line, and means cooperative with said previously mentioncd means for guarding said telephone line during connection with said trunk line from interference by any other telephone line attempting connection with said trunk line.

7. In an automatic telephone system, a plurality of telephone lines, a plurality of relays at the central. ollice each inductive] y associated with one of said telephone lines, a tone circuit, said telephone lines being c ach normally inductively connected to said tone circuit through contacts of its said associated relay, means for automatically operating said relays to break contact bctween any one of said telephone lines and said inductively connected tone circuit and through other contacts on said relays place said telephone line in connection with said trunk line.

8. In an automatic telephone system, a plurality of telephone lines, a plurality of relays at the central ollice each inductively associated with one of said telephone lines, a busy tone circuit, said, telephone lines being each normally inductively connected to said busy tone circuit through contacts of its said associated relay, means for automatically operating said relays to break contact between any one of said telephone lines and said imluctivcly connected busy tone circuit and through other contacts on said relays place said telephone line in connection with said trunk line, and means cooil. Il.

"he I operative with said previously mentioned means for guarding said telephone line dnring connectionwith said trunk line from interference by any other telephone line attempting connection Witb. said trunk line. in a telephone system, a plurality of telephone lines; a pair of normal wires upon which said lines are concentrated and ing to permit the energization of but one relay at a time.

11. In a telephone system, a plurality of telephone lines; a pair of normal Wires upon Which said lines are concentrated and nor mally interconnected; a trunk circuit normall dissociated from said lines; a relay for each of said lines the line from the normal pair to the trunk circuit; means for energizing one of said relays; and contacts Within said energized relay for preventing the energization of any other relay.

a telephone system, plurality of telephone lines; a pair or normal Wires upon which said lines are concentrated. and normally interconnected; trunlr circuit norreally dissociated from said lines; a relay for eachof said lines; meals for initial y ener one of relays; and center,

plurality oi and acting to switch of said relay for oreventing any other relay and for jl oriiiing a part the cnergzzation oi continuing the energization of the energized relay so long as the initial energizing means maintains its condition which initiated the energization.

13. in a telephone system a tone circuit; telephone lines normally connected ther to; a trunk. circuit; means for switching said lines from said tone circuit to said trunk circuit; and further means preventing the switching of a plurality of said\lines simu taneously. x

1 in a telephone system a tone circuit; telephone lines normally connected thereto; a trunk circuit; means for switching said lines from saidtone circuit to said trunk circuit; said means being; operated to re I more a line from said tone circuit only when said trunk circuit is d'sconnected from all lines l5. a telephone system a series of re lays, means for energizing. one of san relays initially, and an interference circuit pertaining to all said relays cpcratii to prevent he operation oi? two of said ielays simultaneously.

lin a telephone system, a

.ic. u series oi relays "rid means for energizingany one of there initially, said means comprising, in a circuit passing through normally closed pairs of contacts, one pair-in each rtlay, said pairs inseries in said circii'it said circuit passing thence to Winor. all of said relays, in n'initiple,

Signed by me at Toronto, county or and I sorince oi? in Witnesses. 

